1. Field of the Invention
The invention relates to a method for providing clients with access to a server service of a server in a network using an OPC UNIFIED ARCHITECTURE (OPC-UA).
2. Description of the Related Art
OPC Unified Architecture (OPC-UA) is a communication protocol and information model for communication between different automation components (devices).
In the case of OPC-UA, all communication relationships occur in a bilateral manner between two end points. In this case, an OPC-UA client establishes a communication channel to an OPC-UA server, and the entire communication between the two occurs within this channel. This applies, in particular, to all read and write access operations, which therefore also includes subscriptions in which clients are informed of value changes in variables.
In practice, the situation often occurs in which a plurality of clients are interested in the same information from a server. In the case of OPC-UA, each of the clients then establishes bilateral communication with the server and requests the same values as the other clients. Examples in which such a situation occurs are a plurality of HMI devices Human Machine Interface (HMI) devices that show the same view of a server state, historian applications, logging, state monitoring and parallel KPI creation Key Performance Indicator (KPI).